Preliminary study on crosswind aerodynamics for a group of road race cyclists

Abstract

Under crosswind conditions, road cyclists experience an extra drag force and a destabilising lateral force. In these conditions a group of cyclists manages to reorganise its spatial formation to minimise these forces forming an echelon, i.e a diagonal single pace line of riders staggered across the road, a configuration which is markedly different from those adopted in wind-free conditions. To study the effect of the crosswind on drag and lateral forces on the riders we performed wind-tunnel experiments using a scale model cyclist and measuring the forces by means of a load cell. Several configurations with one, two, and four cyclists have been investigated varying yaw angles. Results show that, in a basic 4 rider configuration at a 50 $$^{\circ }$$ ∘ yaw angle, a sheltered rider within the echelon experiences less than 30% of the drag of the guttered rider behind the echelon, struggling against the crosswind. Furthermore, we show that an echelon is worth being adopted under crosswind conditions only beyond a 30 $$^{\circ }$$ ∘ yaw angle. At this critical 30 $$^{\circ }$$ ∘ yaw angle the drag on the guttered rider doubles when the gap to the front group increases from 10 cm to 1 m (in real scale). These results can be of interest in defining road cycling race strategies and they allow some significant configurations to be identified and further investigated in more complex experiments.

Wind tunnel evaluation of novel drafting formations for an elite marathon runner

“…The measurements were performed in a wind tunnel of the Laboratoire de Mécanique des Fluides et d’Acoustique, a research facility already used in a recent sports aerodynamics study [12]. The wind tunnel is 1.5 m long with a 40×40 cm square cross-section.…”

“…The free stream velocity U was obtained from a Pitot tube with an accuracy of ±0.1 normalm normals−1. The turbulent flow was also characterized in a previous investigation [12] by means of a single hot-wire anemometer. The thickness of the boundary layer developing at ground level was found to be less than 0.4 cm.…”

“…This idea emerged very early in the scientific literature [8]. Drafting can be used in cycling [9][10][11][12], skating [13], and downhill skiing [14] among others. In marathon running, pacers can be positioned around a top runner to set the desired pace, but they also can decrease the drag force acting on a designated runner.…”

“…The aerodynamic effects of clothing have also been investigated [21]. Finally, similar studies have estimated how the drag forces differ between peloton formations in cycling using experimental [12] and numerical approaches [22].…”

Assessing the weather conditions for urban cyclists by spatially dense measurements with an agent‐based approach

“…In addition, cross‐winds can also destabilise a bicycle. Studies indicate that for cross‐wind speeds larger than the cycling speed, the side forces acting on the bicycle become larger than the drag forces (Kraemer et al, 2021). However, determining a critical wind speed for destabilising conditions would require extensive studies on actual cyclists or using wind tunnels, and thus, we decided to neglect this specific impact.…”